Cinematographic projectors

ABSTRACT

A projector for cinematograph film of reduced gauge is provided with locking means for locking the film-driving element in a position of disengagement from the film, while the projector film drive mechanism for displacing the film-driving element remains in operation. The locking means are rendered inoperable at intervals by electrical impulses synchronized with the projector drive mechanism to cause the driving element to engage the film intermittently at intervals determined by the frequency of the impulses.

[4 Feb. 15, 1972 ....352/ 180 ........352/l80 ....352/169 X ....352/l69X ABSTRACT A projector for cinematograph film of reduced gauge is progelement gement from the film, while the projecism for displacing thefilmdriving element remains in operation. The locking means are renderedinoperable at intervals by electrical impulses synchronized with theprojector drive mechanism to cause the driving eley at intervalsdetennined 10 Claims, 8 Drawing Figures O United States Patent Carignano[s41 CINEMATOGRAPHIC PROJECTORS 3,288,550 11/1966 51111161....

3,481,662 12/1969 Procop my 3,520,596 7/1970 ODonnell et al... [73]Assignee: Silma S.P.A., Turin, Italy 3,533,688 10/1970Painton....................... [22] Filed: 1970 Primary Examiner-LouisR. Prince [21] Appl. No.: 6,083 Assistant Examiner-Joseph W. RoskosAttorney-Sughrue, Rothwell, Mion, Zinn & Macpeak [30] ForeignApplication Priority Data [57] Jan. 29, 1969 Italy....... ....50343-A/69Feb. 22, 1969 Italy.................................50695-A/69 videdwith locking means for locking the mmdrivin 'tion of disenga 52] us.....3s2/1s0 352/169 a 51 111:. .....G63|121/4s mm mecha" [58] Field....352/180, 169

[56] References Cited ment to engage the film intermittent] UNITEDSTATES PATENTS by the frequency of the impulses.

3,489,492 1/1970 Kobler et al. ..........................352/169 1 Ne wm PAIENTEBFEB 15 1912 SHEET 2 0F 5 CINEMATOGRAPHIC PROJECTORS Thepresent invention relates to projectors for cinematograph films ofreduced gauge. The invention concerns principally the problem ofbringing about movement of the film at different speeds ranging fromzero, when the film is stationary, to maximum speed, without varying thespeed of the projector motor, nor of the film driving mechanism driventhereby.

In order to solve the aforesaid problem, the present invention has asits object to provide a projector with a device which permits manualprogramming of the film speed desired, selecting such speed as requiredfrom a range of preset speeds, including zero speed.

Another object of the invention is to provide a projector of theaforesaid type, in which the speed programming device is of simple,strong and economic construction, precise and reliable in operation andeasy and practical in use.

A further object of the invention is to achieve a speed programmingdevice of the aforesaid type, which is easily adaptable both toprojectors of the type in which the element driving the film alwaysmoves in the same plane, and to projectors of the type in which the forkalso shifts transversely, that is, three-dimensionally.

The main characteristic feature of the projector according to thisinvention resides in the provision of means operable to lock the drivingelement in a position of disengagement from the film, while the drivemechanism for displacing the filmdriving element remains in operation,said means being rendered inoperable at intervals by electrical impulsessynchronized with the said drive mechanism.

Further features and advantages of the invention .will be apparent inthe course of the following detailed description which follows, given byway of non-limiting example, with reference to the accompanyingdrawings, in which:

Fig. l is a perspective view of a device for moving the film, which ispart of a cinematographic film projector according to the invention,illustrated in the stop position of the film-driving element;

FIG. 2 is a view, similar to that of FIG. 1, illustrating the deviceunder normal operating conditions, that is with the film-driving elementfree to move;

FIG. 3 is a perspective view illustrating another type of projectorincorporating a device for moving the film according to the invention; 1

FIG. 4 is a front view of part of the film-driving device;

FIG. 5 is a cross section of the part shown in FIG. 4, taken along theline V-V ofFIG. 4;

FIG. 6 is an electrical circuit diagram illustrating the wiring of thefilm-driving device;

FIG. 7 is a perspective view of the part of the film-driving deviceillustrated in FIG. 4, according to one variant of the invention, and

FIG. 8 is a diagrammatic axial section of the part illustrated in FIG.7.

In FIGS. 1 and 2 is illustrated a well-known device for advancing thefilm, of reduced gauge, in a cinematograph projector. The film,indicated in broken outline at A, passes through a gate, indicatedgenerally at l, fitted with a projection frame opening 2. A mirror 3 isplaced behind the frame opening 2 and cooperates with an opticalprojection unit 4 arranged in front of the gate 1.

Within the gate 1 a slit 5 is made, through which project two teeth 6 ofa forked film-driving element 7. The driving element 7 comprises ashaped lever, pivoted so that it can oscillate and slide horizontally ina vertical plane relative to a fixed pivot in 8. p The lever 7 has atthe center a shaped aperture 9 into which a rotary cam 10 engages. Thecam 10 is provided with an interior elongated cavity 11 cooperating witha roller 12 supported by an appendage 7a is integral with the lever 7.

The cooperation of the rotary cam 10 with the aperture 9 and with theroller 12 imparts to the forked element 7 a cyclic displacementfollowing a quadrangular trajectory which lies in a vertical plane,causing successively the engagement of the teeth 6 in respectiveperforations of the film A, the driving of the film by the teeth 6 byone frame, the disengagement of the teeth 6 from the film perforationsand the return of the member 7 to its original position.

A helical return spring 13 anchored to a fixed frame and attached to themember 7 ensures engagement of the teeth 6 of the member 7 in theperforations of the film A during the filmdriving phase, by causingforward displacement of the forked member 7 when the cam 10 permitsthis.

Consequently the rotational speed of the cam 10 determines the speed ofadvance of the film, which is measured by counting how manyframes persecond pass in front of the projection frame opening 2. In traditionalprojectors the speed of the film can be varied by modifying therotational speed of the cam 10.

In the projector according to this invention,'however, the speed ofadvance of the film A can be varied while the speed of rotation of thecam I0 is kept constant by rendering the forked film-driving element 7inactive for some operational cycles in each period of time. If, forexample, the speed of projection is 16 frames per second, the cam 10performs I6 rotations'per second and oscillates the forked element 7 atthe same frequency; if one wishes to have a film speed of one frame persecond, it is necessary in each second to render the forked element 7inactive for 15 consecutive cycles or rotations of the cam 10 and leaveit free to drive the film for the 16th rotation, so that it may completeits operative cycle. Similarly, for a film speed of two frames persecond, the forked element 7 will complete in each second only twooperative cycles, alternated with 7 consecutive rest cycles when theelement 7 is inactive, and so on.

To this end the element 7 has at its rear end a vertically elongatedrectangular aperture 14 which cooperates with a locking membercomprising a horizontal transverse pin 15, carried by an armature in theform of a flat spring 16 which is anchored at one end to a fixed support17 and is displaceable in the direction of the axis of the pin 15, bythe action of an electromagnet 18.

When the electromagnet 18 is deenergized, the elasticity of the flatspring 16 carries the pin 15 into engagement in the aperture 14 of theforked element 7, and consequently the latter is locked and preventedfrom forward displacement. The element 7 cannot therefore engage thefilm A, which remains stationary for the whole time during which theforked element 7 is locked, while the cam 10 nevertheless continues torotate. When, on the other hand, the electromagnet 18 is energized, itattracts the flat spring 16, and the pin 15 is disengaged from theaperture 14, releasing the forked element 7 which can execute its normalfilm-driving movements.

In FIG. 3 there is illustrated an alternative form of driving deviceaccording to the invention, in which a forked driving element 7 havingfilm-engaging teeth 6 is pivoted at 8 and subject to rocking movement ina vertical plane under the action of a radial cam 19, mounted on acoupled to an axial cam 20 which subjects the element 7' to transverserocking movement in a horizontal plane. The combined action of the twocams 19, 20 gives to the forked element 7 a three-dimensional trajectorywhich is well known. Engagement of the element 7 with the earns 19 and20 is ensured by return springs 13.

A stop member 21, movable by means of an electromagnet 18' is arrangedto prevent, when the electromagnet 18' is arranged to prevent, when theelectromagnet 18' is deenergized, the normal transverse rocking movementof the forked element 7' and thereby prevent the advance of the film.When the electromagnet 18 is energized the stop 21 occupies the positionshown dotted and is clear of the path of movement of the element 7'.

In both the embodiments described above the electromagnet 18 or 18 isenergized intermittently, by means of electric current impulsessynchronized to the rotation of the respective cam 10 or earns 19 and20, so as to bring about different speeds of advance of the film, or itscomplete stoppage, without varying the speed of said cam or cams.

One means for controlling the intermittent energization of theelectromagnet 18 or l8 are illustrated in FIGS. 4, and 6.

The electromagnet control means comprise a circular plate 22 keyed to arotating shaft 23 and bearing a number of circumferentially elongatedapertures 24, 25, 26 distributed at equal intervals on the plate 22 invarious numbers on different concentric circles B, C, D; In this examplethere is one aperture 24 on the circle B, there are two apertures 25 onthe circle C, and four apertures 26 on the circle D. These apertures 24,25, 26 cooperate with a pencil-shaped lamp 27 located to one side of theplate 22 and cooperating with a number of photosensitive elements 28,29, 30, located on the other side of the plate 22 in alignment with thelamp 27.

The photosensitive elements 28, 29, 30 form part of an electroniccontrol circuit, shown diagrammatically in FIG. 6, which includes anamplifier 32 arranged to amplify pulses from the photosensitive elementsto energize the coil of the electromagnet 18 (or 18'). The controlcircuit also includes a number of cutout switches 34, 35, 36 which whenclosed insert in the circuit, and therefore bring into operation,selectively, one or other of the aforesaid photosensitive elements 28,29, 30, preventing the others from operating.

An additional cutout switch 33 serves when operated to deenergize theelectromagnet l8, stopping the film completely, and maintaining theforked driving element locked.

The cutout switch 34 activates only one of the photosensitive elements,28, cooperating with the aperture 24 on the innermost circle B of theplate 22. In the example illustrated the photosensitive element 28causes an impulse to be transmitted to the electromagnet 18 for eachcomplete turn of the plate 22, which would correspond to a film advancespeed of one frame per second if the plate 22 has a speed of onerevolution per second. The cutout switch 35 allows activation of onlythe photosensitive element 29, cooperating with the two apertures 25 onthe circle C, in order to cause energization of the electromagnet l8twice in each revolution of the plate 22: This corresponds to a filmspeed of two frames per second if the plate 22 rotates at one revolutionper second. Similarly, the cutout switch 36 allows activation of onlythe photosensitive element 30 cooperating with the four apertures 26 onthe circle D to cause energization of the electromagnet 18 four times ineach revolution of the plate 22.

A further cutout switch 37 makes it possible to keep the electromagnetl8 continuously energized, so as to leave the forked element free and todrive the film normally at the maximum speed of the projector.

By varying the number of photosensitive elements, the number of circleson the plate 22 and the number of apertures on each circle, it ispossible to obtain many different predetermined speeds of advance forthe film.

The device described makes it possible to select and choose a film speedfrom a range of preset speeds extending from zero to a maximum speed,without needing to change the speed of the cam or cams and the drivingmotor of the projector.

Since the device makes use of simple electric and electronic circuits itis inherently reliable and accurate in operation, and is simple inconstruction and assembly.

In FIGS. 7 and 8 there is illustrated a constructional variant relatingto the means for controlling the energization of the electromagnet 18 or18.

, According to this variant a rotating distributor comprising a plate22, made of electrically insulating material, is keyed to a shaft 23which is kinematically coupled to the film-driving mechanism.

The plate 22 has upon its front surfaces a central slip ring 40 and anumber of sliding circumferentially elongated contacts 41, 42, 43,distributed along concentric circles B, D, D and electrically connectedto the central slip ring 40.

Cooperating with the slip ring 40 and with the respective contacts 41,42, 43 are respective sliding brushes 45, 46, 47, 48 carried by aninsulating support 44 extending radially with respect to the center ofand parallel to the contact-bearing surface of the plate 22'.

The innermost brush, 45, which cooperates with the slip ring 40,supplies electric current to the distributor, whilst the other brushes46, 47, 48 make contact at regular intervals upon rotation of the plate22' with the sliding contacts 41, 42, 43, distributed upon the differentcircles B, C and D.

The different brushes 46, 47, 48 are activated selectively by means ofinterruptor switches or other devices, not illustrated, which make itpossible to activate any selected one of these three brushes, accordingto the desired film speed, excluding the other brushes from operation.

Connection of the different sliding contacts 41, 42, 43 to the centralslip ring 40 can be affected, as illustrated in FIG. 8, by means ofleads 410 (one only of which is shown, diagrammatically, in FIG. 8)which lead from the central slip ring 40 to the appropriate contacts,running along the back surface of the distributor plate 22 opposite thesurface on which the contacts 41, 42, 43 are provided.

The reduced rotational speed of the distributor plate 22 ensures longlife of the brushes 46, 47, 48, which are urged resiliently towards theplate 22' so as to remain in contact with the front surface thereof.

The sliding contacts 41, 42, 43 will normally comprise wires embedded inthe front surface of the plate 22' to improve the working conditions ofthe brushes, 46, 47, 48 thereby reducing wear on the latter.

What is claimed is l. in a projector for cinematograph film of reducedgauge, of a type including a drive mechanism and a displaceablefilmdriving element driven by said mechanism for moving the filmintermittently, the improvement comprising means operable to lock thedriving element in a position of disengagement from the film while thedrive mechanism for displacing the film-driving element remains inoperation, means providing electrical impulses synchronized with saiddrive mechanism, and control means responsive to said electricalimpulses to render said locking means inoperable at predeterminedintervals; said film-driving element having means defining an aperture,said means locking the displaceable film-driving element comprising alocking member which cooperates with said aperture in the drivingelement, and said control means including an electromagnet energizablethereby and having a movable armature carrying said locking member.

2. Projector according to claim 1, wherein the electromagnet whenenergized disengages the locking member from said aperture.

3. Projector according to claim 1, including a light source, a number ofphotosensitive elements cooperating with the light source, a rotaryplate formed with apertures distributed on concentric circlescorresponding to the positions of the different photosensitive elementsand interposed between the source and said elements, and preselectionmeans rendering each said element selectively operable to cause theelectrical impulses therefrom to energize the electromagnet.

4. Projector according to claim 3, including additional preselectionmeans effective respectively to deenergize the electromagnet to bringabout the stopping of the film and to cause continuous energization ofthe electromagnet to obtain the maximum film speed.

5. Projector according to claim 1, wherein the control means comprise arotating distributor having a plate of insulating material, a number ofsliding contacts distributed on said plate along concentric circles,respective brushes in correspondence with the respective contacts andpreselection means connecting the said contacts selectively to theelectromagnet, said distributor being further provided with a slip ringand a cooperating brush feeding electric current to the said slidingcontacts.

6. Projector according to claim 5, wherein the slip ring is providedcentrally upon the distributor plate and including leads connecting theslip ring to the different sliding contacts, said leads being disposedon the rear face of the distributor plate remote 'from the face on whichthe. sliding contacts are disposed.

7. In a projector for cinematograph film of reduced gauge, of a typeincluding a drive mechanism and a displaceable filmdriving elementdriven by said mechanism for moving the film intermittently, theimprovement comprising means operable to lock the driving element in aposition of disengagement from the film while the drive mechanism fordisplacing the film-driving element remains in operation, meansproviding electrical impulses synchronized with said drive mechanism,and control means 'responsive'to said electrical impulses to render saidlocking means inoperable at predetermined intervals; said means lockingthe displaceable film-driving element comprising a stop member movableinto and out of the path of movement of the element and an electromagnetengageable through said control means for controlling said movement ofsaid stop member, a light source, a number of photosensitive elementscooperating with the light source, a rotary plate formed with aperturesdistributed on concentric circles corresponding to the positions of thedifferent photosensitive elements, and interposed between the source andsaid elements, and preselection means rendering each said elementselectively operable to cause the electrical impulses therefrom toenergize the eicctromagnet.

8. Projector according to claim 7, including additional preselectionmeans effective respectively to deenergize the electromagnet to bringabout the stopping of the film and to cause continuous energization ofthe electromagnet to obtain the maximum film speed 9. Projectoraccording to claim I. wherein the control means comprise a rotatingdistributor having a plate of insulating material, a number of slidingcontacts distributed on said plate along concentric circles, respectivebrushes in correspondence with the respective contacts and preselectionmeans connecting the said contacts selectively to the electromagnet,said distributor being further provided with a slip ring and acooperating brush feeding electric current to the said sliding contacts.

10. Projector according to claim 9, wherein the slip ring is providedcentrally upon the distributor plate and including leads connecting theslip ring to the different sliding contacts, said leads being disposedon the rear face of the distributor plate remote from the face on whichthe sliding contacts are disposed.

1. In a projector for cinematograph film of reduced gauge, of a typeincluding a drive mechanism and a displaceable film-driving elementdriven by said mechanism for moving the film intermittently, theimprovement comprising means operable to lock the driving element in aposition of disengagement from the film while the drive mechanism fordisplacing the film-driving element remains in operation, meansproviding electrical impulses synchronized with said drive mechanism,and control means responsive to said electrical impulses to render saidlocking means inoperable at predetermined intervals; said film-drivingelement having means defining an aperture, said means locking thedisplaceable film-driving element comprising a locking member whichcooperates with said aperture in the driving element, and said controlmeans including an electromagnet energizable thereby and having amovable aRmature carrying said locking member.
 2. Projector according toclaim 1, wherein the electromagnet when energized disengages the lockingmember from said aperture.
 3. Projector according to claim 1, includinga light source, a number of photosensitive elements cooperating with thelight source, a rotary plate formed with apertures distributed onconcentric circles corresponding to the positions of the differentphotosensitive elements and interposed between the source and saidelements, and preselection means rendering each said element selectivelyoperable to cause the electrical impulses therefrom to energize theelectromagnet.
 4. Projector according to claim 3, including additionalpreselection means effective respectively to deenergize theelectromagnet to bring about the stopping of the film and to causecontinuous energization of the electromagnet to obtain the maximum filmspeed.
 5. Projector according to claim 1, wherein the control meanscomprise a rotating distributor having a plate of insulating material, anumber of sliding contacts distributed on said plate along concentriccircles, respective brushes in correspondence with the respectivecontacts and preselection means connecting the said contacts selectivelyto the electromagnet, said distributor being further provided with aslip ring and a cooperating brush feeding electric current to the saidsliding contacts.
 6. Projector according to claim 5, wherein the slipring is provided centrally upon the distributor plate and includingleads connecting the slip ring to the different sliding contacts, saidleads being disposed on the rear face of the distributor plate remotefrom the face on which the sliding contacts are disposed.
 7. In aprojector for cinematograph film of reduced gauge, of a type including adrive mechanism and a displaceable film-driving element driven by saidmechanism for moving the film intermittently, the improvement comprisingmeans operable to lock the driving element in a position ofdisengagement from the film while the drive mechanism for displacing thefilm-driving element remains in operation, means providing electricalimpulses synchronized with said drive mechanism, and control meansresponsive to said electrical impulses to render said locking meansinoperable at predetermined intervals; said means locking thedisplaceable film-driving element comprising a stop member movable intoand out of the path of movement of the element and an electromagnetengageable through said control means for controlling said movement ofsaid stop member, a light source, a number of photosensitive elementscooperating with the light source, a rotary plate formed with aperturesdistributed on concentric circles corresponding to the positions of thedifferent photosensitive elements, and interposed between the source andsaid elements, and preselection means rendering each said elementselectively operable to cause the electrical impulses therefrom toenergize the electromagnet.
 8. Projector according to claim 7, includingadditional preselection means effective respectively to deenergize theelectromagnet to bring about the stopping of the film and to causecontinuous energization of the electromagnet to obtain the maximum filmspeed.
 9. Projector according to claim 1, wherein the control meanscomprise a rotating distributor having a plate of insulating material, anumber of sliding contacts distributed on said plate along concentriccircles, respective brushes in correspondence with the respectivecontacts and preselection means connecting the said contacts selectivelyto the electromagnet, said distributor being further provided with aslip ring and a cooperating brush feeding electric current to the saidsliding contacts.
 10. Projector according to claim 9, wherein the slipring is provided centrally upon the distributor plate and includingleads connecting the slip ring to the different sliding contacts, saidleads being disposed on the rear face of the distributor plate Remotefrom the face on which the sliding contacts are disposed.